There has been known an electrostatic spray head for discharging fine particles that includes capillary needles and a surrounding surface, each of which at least has a semi-conductive property, and that atomizes liquid in a needle-shaped orifice by application of an electrical potential between the capillary needles and the surrounding surface (see Japanese Unexamined Patent Application Publication No. S63-069555). In this electrostatic spray coating head, a conductor plate (21) supports a large number of capillary needles (11) located in at least two rows such that the distal ends of the capillary needles (11) are positioned in an identical plane. A conductive extractor plate (14) having a large number of circular holes (13) is disposed such that each of the holes (13) is disposed concentrically with respect to one of the needles. The extraction plate (14) is located away from the conductive plate (21) by a constant distance and generates uniform discharge of mist of liquid from the needles (11). A manifold device (15) communicating with the capillary needles (11) supplies the liquid to the rows of the capillary needles (11), and an electrical device (Vi) generates an electrical potential between the respective capillary needles (11) and the extraction plate (14). This gives a thin coating on a web.
In the device like the above-described Japanese Unexamined Patent Application Publication No. S63-069555, which generates the electrical potential (an electrostatic force) to spout the liquid from the capillary needles (nozzles) and spray the liquid, supplying a large amount of liquid to the nozzles generally makes an atomization state (such as a state of a particle diameter of the liquid to be sprayed) of the liquid unstable, and a state where the liquid is not atomized occurs at the worst.
Meanwhile, when the liquid such as a coating material is applied over a coated object, a time taken for the application of the liquid to the coated object can be shortened as an amount of the sprayed liquid increases. Accordingly, the increase in the amount of supplied liquid has been requested.
However, increasing the amount of supplied liquid generates a variation of the particle diameter of the liquid to be sprayed as described above, causing a problem of unevenness of application. When the liquid is in the state of not being atomized, coating the liquid to the coated object itself becomes difficult.
The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide an electrostatic spray device and an electrostatic spray method that ensure stable atomization even when an amount of supplied liquid is large.